Apparatus and methods of sharpening cutting tools

ABSTRACT

An adapter for use with a powered grinding tool having a driven grinding wheel has a pivotally mounting part on a body thereof, and a drill bit holder engageable with the mounting part in either of two orientations for sharpening a tip of a drill bit clamped in a set position in the drill bit holder at the grinding wheel, the engagement being completed when the drill bit engages on a stop bar at the front of the mounting part. Also disclosed is a setting arrangement for setting the drill bit in its holder including stop means for engagement by the drill tip upon longitudinal setting of the drill bit, and drill rotation setting means slidable relative to the stop means for rotational setting of the drill bit. A powered grinding tool having the features of the adapter formed as part thereof is also disclosed.

BACKGROUND OF THE INVENTION

A. Field of the Invention

This invention relates to improvements in drill bit sharpening means,and particularly to an adapter for a power tool of the general formdescribed and shown in our PCT Applications Nos. GB93/00079 (WO93/14903)and GB95/00447 (WO95/23672).

B. Description of the Prior Art

In said PCT applications there is disclosed a powered grinding toolhaving a motor adapted to be driven by power supply means, a rotatableshaft drivable, in use, by the motor, and a rotatable grinding wheel towhich drive is transmitted, in use, from said shaft. Such a poweredgrinding tool will hereinbefore be referred to as being of the kindspecified. Adapters are described for releasable engagement with saidtool. However the feature(s) for working an implement provided by eachadapter can be provided as part of the tool if the `adapter` is formedas a non-releasable part of the tool.

SUMMARY OF THE INVENTION

According to one aspect of the invention there is provided an adapterfor use with a powered grinding tool of the kind specified, the adaptercomprising a body having a mounting part, and a drill bit holderengagable with said mounting part in either of two orientations, themounting part having location means engagable, in use, by the holderand/or a drill bit carried by said holder, the arrangement being suchthat, in use, the drill bit can be sharpened by said grinding wheel uponengagement of the holder with said mounting part, said engagement beingcompleted when the holder and/or the drill bit engages said locationmeans, engagement of the holder in its said two orientationsrespectively allowing for sharpening of respective opposite faces/edgesof the drill bit.

According to another aspect of the invention said `adapter` is formed aspart of the grinding tool, instead of being separately releasablyfittable thereto, so that a self-contained sharpener tool is provided.

According to a still further aspect of the invention there is provided asetting arrangement for setting, in a drill bit holder, a drill bithaving a tip to be sharpened, the drill bit holder intended to belocated adjacent grinding means for effecting sharpening the tip of theset drill bit, the setting arrangement comprising engagement means forreleasably engaging the drill bit holder during setting, stop means forengagement by said drill tip upon longitudinal setting movement of thedrill bit in said drill bit holder, and drill rotation setting meansmovable relative to the stop means and having an engagement surface, theoperation being such that, in use, with the drill rotation setting meansdisposed in a forward position relative to the stop means, saidlongitudinal setting movement of the drill bit causes one side of thetip thereof to engage said engagement surface of the setting means and,if the tip is spaced from the stop means, to move the setting meansrelative to the stop means until the tip engages the stop means, thedrill bit being in its correct rotational orientation when the drill bitis in engagement with the stop means, said one or another side of thedrill bit tip is in engagement with said engagement surface, androtation of the drill bit causes no movement of the setting meansrelative to the stop means.

Preferably the engagement surface is a surface at an angle to thedirection of longitudinal setting movement of the drill bit. Desirablythe engagement surface is one of a pair of engagement surfaces defininga V-shaped recess in the front of the setting means, and convenientlythe surfaces converge to a central slot through the setting means whichreceives the stop means relative to which the setting means can slide.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example, with referenceto the accompanying drawings, in which:

FIG. 1 is a schematic front perspective view of an adapter of one aspectof the invention for use with a powered grinding tool for sharpeningdrill bits, a grinding wheel of the tool also being shown,

FIG. 2 is an exploded view of a drill bit holder of the adapter,

FIG. 3 shows how the drill bit holder is positioned at a location of abody of the adapter correctly to set the drill bit position in theholder,

FIG. 4 is an enlarged end view of the drill bit correctly positioned inthe holder,

FIG. 5 is a plan view of the holder at said location of the body withthe drill bit correctly positioned,

FIG. 6 is a perspective view of a mounting cradle of the adapter,

FIG. 7 is a schematic, fragmentary perspective view of the adapter witha drill bit holder in position to be fitted to a mounting cradle in oneof its orientations,

FIG. 8 is fragmentary side view showing the holder fully engaged withthe mounting cradle,

FIG. 9 is a fragmentary perspective view of the holder with the drillbit carried thereby engaged against stop means of the mounting cradle,

FIG. 10 is an exploded perspective view of a further adapter of said oneaspect of the invention, the adapter incorporating a drill bit settingarrangement of a further aspect of the invention,

FIG. 11 is an enlarged perspective view of part of the adapter of FIG.10,

FIG. 12 is a view like FIG. 11, with a drill rotation setting componentshown fitted in position,

FIG. 13 is a view like FIG. 12, with a drill bit holder fitted inposition for drill bit setting,

FIG. 14 is a view like FIG. 13, with the drill bit holder and the drillbit set therein engaged with a mounting cradle part of the adapter readyfor sharpening,

FIG. 15 is a scrap view showing a drill bit tip correctly set up in thedrill bit holder in respect of its rotational orientation, and

FIG. 16 is a scrap view of an alternative form of a wall of part of thesetting arrangement.

DETAILED DESCRIPTION

As mentioned hereinabove, this invention relates, in one aspect, to anadapter for use with, or as part as, a powered grinding tool of thegeneral form described and shown in said PCT Applications. The toolforms no part of the present invention, and will thus not be described,reference being made to said PCT Applications for details thereof.

The adapter 10 has a casing body with a downwardly and outwardly slopingplatform 11 across its front face 12, approximately mid way between itsupper and lower ends. The interior of the body is adapted to receivetherein a grinding wheel 13 of the powered grinding tool, to which theadapter is releasably fitted in the usual manner, for example byprojections on its opposite outer sides slidably engaging with verticalcomplementary slots at opposite sides of the working face of the tool,or vice versa. One projection 14 is shown, and latch means of the toolwould automatically engage the adapter, in use, to retain it in place,so that the wheel 13, which is accessible at an open part of the frontface 12 above the platform, is correctly positioned relative to theadapter platform.

The adapter is intended for use with the powered grinding tool forsharpening drill bits, e.g. standard bits for twist drills, bits forsplit point drills etc. To this end the adapter also comprises a drillbit holder 15, which is slidably engagable in either of twoorientations, 180° apart, with a mounting cradle 16 angularly movablymounted on the platform 11.

The drill bit holder is shown best in FIG. 2. It has a base 17 in theform of a V-block, with an upstanding end 18 through which the V-groove19 continues, the groove being to receive a drill bit 20 as shown.Opposite upright sides of the end 18 are formed with respectiveoutwardly facing grooves 21, 22. The drill bit is clamped, in use, inthe V-groove by a top jaw 23 which has a slot therein in which isreceived a knurled circular nut 24 having an internal screw thread. Thenut is threadedly engaged with a split, externally threaded moulded bolt25, the opposite sides of which are on opposite sides respectively ofthe V-groove. Thus by screwing the nut down onto the bolt, the drill bitcan be clamped by the jaw 23 in an adjusted position and orientation inthe groove 19.

In order accurately to set the drill bit in the holder, so that it canbe correctly ground when the holder is engaged with the cradle 16, theplatform is provided with a locating slot 26 communicating with aconfigurated recess 27 at a front edge of the platform, at which theholder is arranged to engage and locate. The slot 26 is generallysemicircular in cross-section, extending normal to the recess 27. Theslot has an angled inner end face 28, for a purpose to be explained.

The mounting cradle 16 has a base 29 on the sloping platform 11, with apair of side arms 30, 31 respectively upstanding normally therefrom,these being cut down away from the front of the cradle adjacent the rearof the platform 11. Opposite inner surfaces of the respective arms 30,31 at the end of the cradle adjacent the rear of the platform are formedwith respective tongues 32, 33 or equivalent which are complementary inshape to the grooves 21, 22 of the holder 15. In this way, the holdercan be slidably engaged with the cradle through the relative movement ofthe tongues into said grooves.

A horizontal datum cross-bar or stop-bar 34 extends between the arms 30,31 at the end of the cradle where said tongues are formed, this stop-barbar however lying outwardly of the tongues and being disposedapproximately half way between the top and bottom of this cradle end.The cradle is pivotally mounted on the platform 11 by a pivot 35 at thebase 29.

In use, a drill bit 20 to be sharpened is placed in the V-groove 19 withthe top jaw 23 well spaced therefrom, and possibly even separated fromthe base 1 7. The jaw 23 is then screwed down onto the base until thedrill bit is loosely held in the groove 19. The drill bit needs to beclamped so that it projects by the sum of a distance X (FIG. 8) and afurther small distance Y (FIG. 5) corresponding to the amount ofsharpening required. Also it needs to be rotationally orientated so thatthe drill edges can be correctly offered to the wheel 13 duringsharpening. These requirements can be met in a variety of ways, thesimplest being by ruler and eye. However in this example, the slot 26 isintended to be used.

Accordingly after manually adjusting the loosely held drill bit 20 inthe groove 19 to a first guess at its correct axial and rotationalstate, the holder is positionally engaged on the platform 11 at therecess 27, with the drill bit being received in the slot 26, as shown inFIGS. 3 and 5. The drill bit is manually adjusted so that it liesagainst the shorter side of the slot, with its end engaging against theangled slot end face 28 (FIG. 5). The drill bit now extends from theholder by the required distance of X+Y. Additionally, the drill bit isrotated to align one of its opposite cutting faces/edges with the face28, thereby providing the correct rotational orientation for sharpening(FIG. 4). With the drill bit now set in its holder, the top jaw isscrewed down tightly onto the base 17, so as to clamp the drill bit inits correctly adjusted position.

The holder is now transferred to the cradle 16 and slidingly engagedtherewith as described previously, by gradually lowering it towards thebase 29. Simultaneously with said lowering, it is intended that thecradle is swung about its pivot 35 from side to side. Accordingly theone drill bit face is sharpened by the rotating grinding wheel as thelowering and swinging movement takes place. The lowering terminates whenthe drill bit engages the stop-bar 34 (FIG. 9), this corresponding to aprojection of the drill bit from its holder by the distance X (FIG. 8),with the distance Y corresponding to the amount of the bit ground awayby the sharpening process. The opposite drill bit face of the two facesshown in FIG. 4 is sharpened by removing the holder from the cradle,turning it through 180° and re-engaging the holder by lowering it asdescribed until the drill bit engages the stop-bar. Instead of thisengagement being by the drill bit, it could instead be by part of theholder, or by both the drill bit and the holder.

The process described ensures that the two faces are groundsymmetrically, because each grinding operation stops when the datumcross-bar is engaged by the drill bit. This arrangement can be used withstandard twist drill bits and also split point drill bits and others.

The cradle can be provided with adjustable stops to control the angularmovement thereof to give appropriate backing off and cutting angle. Itcould also be tiltable by suitable means to vary the drill tip angle.Such features are particularly desirable when sharpening split pointdrill bits.

Instead of the grooves and tongues described for slidably engaging theholder on the cradle, it would be possible to use the reversearrangement or any suitable alternative means, i.e. holes which locateon pins, dovetail slots, or other variations which provide location withonly one degree of freedom of movement.

The provision of the stop-bar compensates for the fact that although asmall diameter drill bit engages in the V-groove as shown in FIG. 4, alarger diameter drill bit engages further up the side of the groove.

The illustrated embodiment of the invention thus provides a relativelysimple drill bit holder engagable with a simple cradle in a controlledmanner, i.e. only generally perpendicular to the drill bit axis. Theholder can be easily lifted from the cradle, turned over and replaced,to grind the other drill face. Grinding is easily effected by angularmovement of the cradle whilst pressing down the holder until the drillstops against a datum cross-bar. This guide feature and datum cross-barensures that each side is ground identically.

Instead of the adapter being separate from the tool, the sharpening`means` provided could be incorporated in an arrangement which is fixedto a grinding tool. Thus a self contained drill bit sharpening toolwould be formed which provides the advantageous features of the adaptersharpener system referred to, even though it does not require a separateadapter.

Instead of using the location slot 26 and recess 27 of the platform toset the drill bit to be sharpened, there is now described an alternativearrangement where setting is carried out at the mounting cradlecomponent. As with the embodiment of FIGS. 1 to 9, the arrangement,which is also itself separately inventive according to another aspect ofthe invention, is applicable either with a separate adapter or with aself-contained powered grinding tool where the features of the adapterare an integral part of the tool. However for consistency with thedescription of the embodiment of FIGS. 1 to 9, this alternativeembodiment will be described in relation to a separate adapter which isreleasably engageable with a separate powered grinding tool.

The basic body of the adapter 110 shown in FIG. 10, is very similar tothat of the first embodiment, but has a slightly greater rearwardlyextending top wall 111. The adapter body has a platform 112 slopingdownwardly and outwardly across its front face, in the same manner andwith the adapter of the first embodiment and has its front face abovethe platform formed with an opening 113 at which a grinding wheel (notshown) is received flush. One projection 114 is shown at the front lefthand side of the adapter body to enable the adapter to be releasablyfitted in the usual manner with the powered grinding tool, the otherprojection at the opposite side of the body not being shown. In thefront face of the adapter body below the platform 112 there can beprovided a slot 115 for latching the adapter to the tool body, althoughreleasable latching engagement can be provided between the grinding toolbody and the adapter in any other convenient manner.

As with the first embodiment, the adapter is intended for use with thepowered grinding tool for sharpening drill bits, e.g. standard bits fortwist drills, bits for split point drills etc. A drill bit holder ofsimilar form to that of the first embodiment is still provided, and, forthe sharpening operation, this is still engaged with a mounting cradlewhich is angularly movably mounted on the platform 112. However as willbe described, the means for setting the drill bit in the drill bitholder is no longer formed on the platform, but is instead incorporatedinto and alongside the component which includes the mounting cradle, asshown, for example in detail, in FIG. 11. Additionally the setting meansnow incorporates an improved method of catering for differently sizeddrills, as will be described hereinafter.

As shown best in FIG. 10, the drill bit holder 116 has a base 117 in theform of a V-block, with its one end being formed by a pair of spaced,upstanding parallel sides 118, 119 respectively connected by acrosspiece 120 spaced above the V-groove 121 which continues to the endof the block. The respective outer surfaces of the upstanding sides 118,119, are formed with respective grooves 122. The drill bit 124 isclamped, in use, in the V-groove by a top jaw or clamp bar 125 which hasa slot therethrough in which is received a knurled circular nut 126having an internal screw thread. The nut is threadedly engaged with asplit, externally threaded moulded bolt 127, the opposite sides of whichare on respective opposite sides of the V-groove. Thus by screwing thenut down onto the bolt, the drill bit can be clamped by the top jaw 125,so that drill bit 124 can be adjustably positioned with a particularorientation in the groove 121.

In the first embodiment, there is provided a mounting cradle 16 which isangularly movably mounted on the platform of the adapter, the cradleproviding means for engaging the drill bit holder therewith so that withthe drill bit having been correctly set in the holder, the holder isthen correctly positioned relative to the grinding wheel for correctsharpening of the drill bit tip. With the illustrated embodiment of thepresent invention, the mounting cradle is formed as part of a swivelbase component 128 in the form of a plastics material moulding, the basecomponent 128 also incorporating, as part thereof, a setting arrangementto enable the position and orientation of the drill bit 124 correctly tobe set. As with the mounting cradle 16, the base component 128 is againarranged to be angularly movably mounted on the platform 112, therotation axis being denoted at 129 for component 128, and for platform112 at axis 129a in a recess 130 generally at the centre of the rear ofthe platform adjacent the opening 113, as shown in FIG. 10. However thebase component 128 could be pivotally arranged on the platform 112 byany other convenient means, so that, as will be described, it can beangularly moved about the plane of the platform 112 to provide thenecessary sharpening of the drill bit tip.

The mounting part of a component 128 is of similar form to the mountingcradle 16, in that it provides a base 131 on which the drill bit holderis received. The mounting part has a pair of side arms 132, 133respectively upstanding normally from the base, these being cut downaway from the front of the mounting part which is adjacent the rear ofthe platform 112. These side arms are formed with facing arcuateportions to accommodate nut 126 when the holder 116 is inverted toengage the mounting part, as will be described. Opposite inner surfacesof the respective side arms are formed with respective tongues 134, 135or equivalent which are complimentary in shape to the grooves 122, 123of the drill bit holder 116. In this way, the holder can be slidablyengaged with the mounting part through the relative movement of thetongues into said grooves. In the engaged position, the base 117 engageson the base 131 of the mounting part.

A horizontal datum cross-bar or stop-bar 136, preferably of metal,extends between the arms 132, 133 at the end of the mounting part wherethe tongues are formed, this stop-bar lying outwardly of the tongues andbeing disposed approximately half-way between the top and bottom of thismounting part end. This stop-bar is thus of the same form as stop-bar 34of the mounting cradle 16. At the front end of the mounting part, thereis an upstanding end surface formed at its upper extremity with asemi-cylindrical recess to accommodate the end of the drill bit whichprojects from the drill bit holder.

In use, a drill bit 124 to be sharpened is placed in the V-groove 121with the top jaw 125 well spaced therefrom, and possibly even separatedfrom the base 117. The jaw 125 can be screwed down onto the base untilthe drill bit is loosely held in the groove 121. The drill bit needs tobe clamped so that it projects by the sum of a distance X and a furthersmall distance Y corresponding to the amount of sharpening required,these distances being as shown and described with the first embodiment,and in particular in relation to FIGS. 5 and 8. Additionally the drillbit needs to be rotationally orientated so that the drill edges can becorrectly offered to the grinding wheel during sharpening. Theserequirements can be met in a variety of ways, the simplest being byruler and eye. However in this example, the base component 128 providessuitable setting means alongside the mounting part thereof, and anaspect of the present invention relates to this setting arrangement perse. As previously mentioned, the setting arrangement could be formedinstead on a fixed or moveable part of a self-contained poweredsharpening tool, rather than on a fixed or moveable part of an adapterfor releasable engagement with a powered grinding tool. Although it isconvenient for the setting arrangement to be on the same component asthat which provides the mounting part for the drill bit holder, this isnot essential, and the setting arrangement could instead be provided ona separate part of the adapter, e.g. as with the first embodiment, onpart of the platform 112. Clearly, however any setting is related to thesubsequent use of the `set` holder at the mounting part of component128.

As illustrated, the setting arrangement comprises a first channel havingparallel sides 137a, 137b and a flat base 138. The inner end of thisfirst channel is closed by a wall 139 normal to the base 138, andhaving, in the illustrated embodiment a central V-shaped notch in itsupper surface. However in an alternative preferred form of wall 139,diagrammatically shown as 139a in FIG. 16, the upper surface of the wallhas a central flat part, matching the upper surface of stop-bar 136,with respective upwardly angled parts at its sides. Behind the wall 139,is formed a second channel with a flat base 140 parallel to, but at ahigher level than, the base 138. As can be seen from the Figures, theside 137a is stepped upwardly alongside the whole of the flat base 140,and for part of the flat base 138 adjacent wall 139. The other side 137bis similarly stepped, with its part alongside the base 140 being in factextended upwardly to a greater extent in that it forms the side arm 132of the mounting part of the base component 128. Adjacent the wall 139,respective interior surfaces of sides 137a and 137b are formed withrespective tongues 141, 142 which are identical to the tongues 134, 135so that they can be received in the grooves 122, 123 of the drill bitholder when this is engaged at the setting means of the base component128, these tongues being spaced from the wall 139 to allow theforwardmost part of the sides 118, 119 to be received therebetween, asshown in FIG. 13.

Accordingly as shown in that Figure, the drill bit holder can engagewith the tongues 141, 142, with the remainder thereof being receivedgenerally in the first channel and having the adjustment nut disposedjust above or in contact with the upper surfaces respectively of thelower parts of the stepped sides 137a, 137b, the bottom of the V-blockengaging on the flat base 138 as shown.

Upstanding from the base 140 and disposed centrally thereof and parallelto the sides 137a and 137, is an upstanding drill bit distance set-uppeg or stop 143, preferably of metallic material. The stop is in thegeneral form a plate spaced rearwardly from the wall 139 approximatelyhalfway along the second channel. The stop has a rearwardly upwardlysloping front face 144, and longitudinally slidably arranged in thissecond channel is a drill rotation set-up element 145. Arranged in thebase 140 along respective opposite sides of, and parallel to, the stop143, are a pair of equi-spaced slots, one of which 146 is shown in FIGS.10 and 11.

The element 145 is in the form of a generally square block which has aV-shaped recess 147 in its front face, the respective facing angledsides of the recess converging towards the rear face of element 145.Said angled sides, as well as the respective front surfaces of theelement 145 at opposite sides of the recess, may be formed withrespective liners, each of which could be secured by adhesive or thelike to the angled inner surface of the recess and the outer flat frontsurface adjacent thereto. Each liner may be anchored to its associatedfront face by having a turned-over end received in a slot in said frontface. At the inner extremity of the recess, to which, as stated, the twoangled faces thereof converge, there is a central through-slot whichextends to the rear face of the element 145. However the through-slotdoes not extend through the full height of the element 145, butterminates short at the top thereof so as to leave an upper connection.However the through-slot is of such a height that it enables the stop143 be received therethrough as the element 145 slides longitudinallyrelative to said stop, as will be described, in use. The two arms of theelement 145 formed by the dividing through-slot 149, have respectiveprojections 148, 149 on their respective lower surfaces, theseprojections snap-fitting into the pair of slots in the base 140, so asto retain the element 145 in engagement with the component 128 but toallow sliding thereof, in that the projections are of a shorter lengththan the slots. A forwardmost position of the element 145 can be definedby the front surfaces at respective opposite sides of the recess 147engaging the wall 139. In this position the angled front face 144 of thestop 143 is received almost at the inner extremity of the recess 147,with its rear end projecting slightly from the rear of the element 145out of the through-slot 149. However the forwardmost position of theelement 145 could be rearwardly of this, but normally with the frontfaces at opposite sides of the recess being at least level with orforward of the front face 144. As far as the rearmost position of theelement 145 is concerned, it is convenient for this to be either whenits front faces at opposite sides of the recess are level with the frontface 144, or alternatively when the flat rear face of the element 145 isflush with the rear of the component 128 defined by the sides 137a,137b.

The element 145 can be retained other than by way of projectionssnap-fitting in respective recesses, for example by respective pegs onopposite sides of the element slidably engaging in slots in therespective sides 137a, 137b, without any snap-fit. Additionally theelement 145 could be spring-biased forwardly, although this can makeremoval of the drill bit holder and clamped drill bit somewhat moredifficult. This also suffers from the disadvantage that it can push thedrill bit away from the stop 143 during clamping. In fact it may bepossible to allow for longitudinal sliding of the element 145 withoutany specific guiding means other than the sides 137a, 137b and base 138.The sloping front face 144 of the stop peg 143 is designed to correspondto the angle on a drill bit. Instead of the whole of the front facesloping, it can be convenient for the lowermost part to be a verticalface with the sloping part extending therefrom partway up the peg.

Use of the setting arrangement will now be described.

Firstly after manually adjusting the loosely held drill bit 124 in thegroove 121 to a first guess at its correct axial and rotational state,the holder is positionally engaged at the setting arrangement by slidingit downwardly towards the flat base 138 with the tongues 141, 142 beingreceived in the grooves 122, 123 respectively, until the positiongenerally shown in FIG. 13 is reached. At this time, or previous to theengagement of the drill bit holder, the drill rotation set-up element145 is slid forward in the second channel to its forwardmost position,shown generally in FIG. 12, where the front face 144 of the stop 143 isat the rear of the recess 147.

Generally the initial rough positioning by guesswork of the drill bit inthe drill bit holder will mean that when the drill bit holder is engagedin the first channel, as shown in FIG. 13, the drill bit tip will bespaced from the front face 144 in order to allow the holder to seat onbase 138. If this is not the case, if the drill bit is too far forwardlyout of the holder, it will be necessary to release any light clampingforce on the drill bit and to move it away from the face 144.Alternatively the drill bit holder can be engaged in the first channelwith the clamp bar 125 well clear of the groove 121, so that the drillbit can then be inserted, any clamping only taking place once correctadjustment has been effected. With this latter procedure, the drill bitis moved forwardly towards the stop 143, with the element 145 in itsforwardmost position. This causes the opposite sides of the drill bittip to engage the opposite sides of the recess 147 whilst the tip isstill clear of the front face 144. This will particularly be the casewith a larger drill bit, for example a 10 mm drill bit, with the resultthat continued forward movement of the drill bit will push the element145 rearwardly along the second channel of the setting arrangement. Thismovement will continue until the drill tip engages the front face 144.This sets the correct longitudinally adjusted position of the drill bitand ensures that it projects from the drill bit holder by the distanceX+Y, referred to in FIG. 5. In contrast to a 10 mm drill bit, a 3 mmdrill bit may well touch the stop 143 and the sides of the V-shapedrecess 147 without significantly moving the element 145 rearwardly,given its much smaller sideways extent. With either the wall 139 or thewall 139a, the drill bit engages the upper V-shaped or flat surfacethereof respectively, such engagement being equivalent to engagement ofthe drill bit against stop-bar 136, described hereinafter.

In order to ensure correct sharpening of the drill bit when the `set`drill bit in the drill bit holder is engaged with the grinding wheel, itis necessary to ensure that the corners C of the drill bit (FIG. 15) arecorrectly aligned, and this involves ensuring that these corners touchthe sides of the V-shaped recess, in other words that the tip is not at90° to the position shown in FIG. 15. Accordingly to check the drill bitrotational orientation, the drill bit can be rotated , i.e. twisted, inits longitudinally adjusted set position, or during longitudinaladjustment. If the longitudinal adjustment has been carried out with theorientation of the drill bit at 90° to that shown in FIG. 15, then thisrotation will bring the corners to the FIG. 15 position, and this willgenerally cause a further slight rearwards movement of the element 145,as the greater sideways extent of the now correctly rotationallyorientated drill bit engages the respective sides of the recess 147.Accordingly in the correct `set` position, the tip of the drill bitengages the stop, and the respective opposite sides/corners of the drillbit engage the respective opposite sides of the recess, with annularrotation of the drill bit causing no further rearwards movement of theelement 145. In this `set` position, full clamping of the clamp bar 125can be effected so that the drill bit is now set.

The drill bit holder is then removed from the setting arrangement andrepositioned at the mounting part of the base component 128 asdescribed. The remainder of the sharpening process is as described inthe first embodiment. Accordingly the drill bit holder is graduallylowered towards the base 131 until the drill bit tip almost touches thegrinding wheel. The grinding wheel is then switched on and the drill bitholder is gradually lowered whilst simultaneously with said lowering,the swivel base component 128, with the engaged holder, is swung aboutits pivot from side to side. The one drill bit face is sharpened by therotating grinding wheel as the lowering and swinging movement takesplace. The lowering is terminated when the drill bit engages the metalstop-bar 136, this corresponding to projection of the drill bit from itsholder by the distance X, with a distance Y corresponding to the amountof the bit ground away by the sharpening process. A typical engagementangle of 118° between the drill bit and the grinding wheel is the sameas the angle of engagement of the drill bit with the stop 143, i.e. whenthe drill bit is correctly set. The opposite drill bit face of the twofaces shown in FIG. 15 is sharpened by removing the holder from themounting part, turning it through 180° and re-engaging the holder bylowering it as described until the drill bit engages the stop-bar 136.As before, instead of this engagement being by the drill bit, it couldbe instead by any part of the holder, or by both the drill bit and theholder.

Accordingly it is ensured that the two faces are ground symmetrically,because each grinding operation stops when the datum stop-bar is engagedby the drill bit. The arrangement can be used with standard twist drillbits and also split point drill bits and others. The component 128 canbe provided with adjustable stops to control the angular movementthereof to give appropriate backing-off and cutting angle. It could alsobe tiltable by suitable means to vary the drill tip angle. Such featuresare particularly desirable when sharpening split point drill bits. Allother variations referred to in our prior specification apply equally,where appropriate, to the present invention.

It will, however, be appreciated, that the setting arrangement of thissecond embodiment could be used to provide a drill bit holder, with setdrill bit, which could then be used with any appropriate matching mountfor use with any appropriate sharpening means, the setting arrangementthus not being restricted to use with a grinding wheel as shown herein,either by way of a separate adapter or by way of the features of theadapter being integral with the grinding tool. It will be appreciatedthat instead of two symmetrically arranged angled engagement surfaces,the element 145 could have a single surface for engagement by the drillbit.

If axial and/or rotational adjustment of the drill bit in the drill bitholder is to be made by eye, this setting could be delayed so as not totake place until the drill bit holder is engaged at the top of themounting cradle, and prior to the holder being lowered and the cradlepivotted as described.

It will be appreciated that the sharpening arrangement comprising thecombination of a mounting part or cradle with location means, such as adatum stop bar, together with a drill bit holder engagable in twoalternative orientations with the mounting part, can be utilisedseparately from an adapter, and also without being part of a grindingtool. In other words such a sharpening arrangement constitutes a furtherindependent inventive aspect, which can be used with any suitablegrinding means.

What is claimed is:
 1. A method of sharpening a cutting tool with agrinding surface by removing a predetermined thickness of a cuttingsurface on said cutting tool, said method comprising:mounting saidgrinding surface with respect to a fixed body; pivotally mounting aguide on said body on a pivot axis oriented at an angle to said grindingsurface; fixing a tool to be sharpened in a tool holder; mounting saidtool holder on said guide for sliding motion with respect to said guidealong a linear path directed parallel to said pivot axis and transverseto said grinding surface; confining the motion of said tool holder, withrespect to said guide, to said sliding motion along said linear path;sliding said tool holder along said linear path until said tool abutssaid grinding surface; pivoting said mounting guide on said pivot axiswhile maintaining said tool in abutment with said grinding surface; andobstructing said tool holder from further movement along said linearpath after said tool holder has moved along said linear path apredetermined distance as a function of said thickness.
 2. The method ofclaim 1 wherein said confining step includes providing said guide andsaid tool holder with sliding tongue-and-groove joints that enable onlysliding motion between said guide and said tool holder.
 3. The method ofclaim 2 wherein said sliding step includes orienting said tool holder inan upright position when sliding said tool holder along said linearpath, and orienting said tool holder in an inverted position whensliding said tool holder along said linear path.
 4. An adapter forguiding the movements of a cutting tool with respect to a grindingplane, said grinding plane adapted to contain a tool-sharpener surfacecapable of sharpening at least first and second complementary cuttingsurfaces of a cutting tool by grinding a predetermined thickness of thecomplementary cutting surfaces, said adapter comprising:a body fixedwith respect to said grinding plane; a mounting guide pivoted to saidbody for rotation about a pivot axis oriented at a first angle withrespect to said grinding plane; a tool holder having clamp means foradjustably clamping a cutting tool in a predetermined position withinsaid tool holder; joint means having a first joint fixed to saidmounting guide and a second joint fixed to said tool holder, said jointmeans enabling said first joint to mate with said second joint such thatsaid tool holder selectively mounts in said mounting guide in first andsecond orientations, said joint means having means for confining saidtool holder to move with respect to said mounting guide along a linearpath directed parallel to said pivot axis such that said firstcomplementary cutting surface lies in said grinding plane when said toolholder is in said first orientation and said cutting tool is beingsharpened, and said second complementary cutting surface lies in saidgrinding plane when said tool holder is in said second orientation andsaid cutting tool is being sharpened; and a limit means fixed on saidmounting guide for limiting the extent of said confine d path by anamount that is a function of said predetermined thickness.
 5. Theadapter of claim 4 wherein said limit means includes a rigid arm fixedto said mounting guide for engaging a cutting tool and obstructingmovement of said tool holder a long said confined path.
 6. The adapterof claim 4 wherein said first joint mates with said second joint to forma sliding joint.
 7. The adapter of claim 4 wherein said tool holder isin an upright position when in said first orientation and is in aninverted position when in said second orientation.
 8. The adapter ofclaim 4 wherein said tool holder comprises a V-block capable ofreceiving an elongated cutting tool, a clamping jaw, and means forengaging said clamping jaw with said V-block to selectively clamp anelongated cutting-tool in said V-block.
 9. The adapter of claim 4wherein said body includes a platform having a planar surface slopedwith respect to said grinding plane, and said mounting guide pivotallyslides on said planar surface with said pivot axis perpendicular to saidplanar surface.
 10. The adapter of claim 9 wherein said planar surfaceforms an obtuse angle with said grinding plane.
 11. The adapter of claim4 wherein said tool holder includes a seat with a longitudinal axis forholding an elongated drill bit with a tip to be sharpened, and furtherincluding a setting means for orienting an elongated drill bit in saidseat along said longitudinal axis in preparation for sharpening.
 12. Theadapter of claim 11 wherein said setting means mounts on said mountingguide and comprises:a tool-holder mount; a tip-stop means for engaging atip of a drill bit to be sharpened upon longitudinal setting of thedrill bit in said seat when said tool holder is mounted in saidtool-holder mount; and drill-rotation-setting means mounted for movementwith respect to said tip-stop means and having tip-abutting surfaces forengaging complementary cutting surfaces of a tip to be sharpened, andmoving said drill-rotation-setting means with respect to said tip-stopmeans until said tip to be sharpened engages said tip-stop means and atleast one of the complementary cutting surfaces engages one of saidtip-abutting surfaces.
 13. The adapter of claim 12 wherein saiddrill-rotation-setting means includes at least one planar surfaceoriented at an angle to said longitudinal axis.
 14. The adapter of claim12 wherein said drill-rotation-setting means includes a pair of planarsurfaces oriented at an angle with each other and with respect to saidlongitudinal axis to define a V-shaped recess.
 15. The adapter of claim14 wherein said pair of planar surfaces are separated by a slot locatedin a plane of said tip-stop means, whereby said slot receives saidtip-stop means when said drill-rotation-setting means moves with respectto said tip-stop means.
 16. The adapter of claim 12 wherein saidtip-stop means includes a face sloping with respect to said longitudinalaxis for engagement by a tip to be sharpened.
 17. The adapter of claim16 wherein said face has a slope angle that is a function of the anglebetween said grinding plane and said pivot axis.
 18. The adapter ofclaim 12 wherein said tool-holder mount and said tool holder form asliding tongue-and-grove joint.
 19. A drill-bit-setting apparatus forsetting, in a drill-bit holder, a drill bit having a tip to besharpened, the drill-bit holder to be located adjacent a grindingsurface for sharpening a tip of the drill bit, said drill-bit-settingapparatus comprising:a mounting means for selectively mounting saiddrill-bit holder during setting of a drill bit; a ti p-stop means forengaging a tip of a drill bit to be sharpened upon longitudinal settingof the drill bit in said tool holder along a longitudinal axis whenmounted in said mounting means; and drill-rotation -setting meansmounted for movement with respect to said tip-stop means and having atip-abutting surface for engaging a cutting surface of a tip to besharpened to move said drill-rotation-setting means with respect to saidtip-stop means until said tip to be sharpened engages said tip-stopmeans and said cutting surface engages said tip-abutting surface. 20.The apparatus of claim 19 wherein said tip-abutting surface includes atleast one planar surface oriented at an angle to said longitudinal axis.21. The apparatus of claim 19 wherein said tip-abutting surface includesa pair of planar surfaces oriented at an angle with each other and withrespect to said longitudinal axis to define a V-shaped recess located ata front of said drill-rotation-setting means.
 22. The apparatus of claim21 wherein said pair of planar surfaces are separated by a slot locatedin a plane of said tip-stop means, whereby said slot receives saidtip-stop means when said drill-rotation-setting means moves with respectto said tip-stop means.
 23. The apparatus of claim 19 wherein saidtip-stop means includes a face sloping with respect to said longitudinalaxis for engagement by a tip to be sharpened.
 24. The apparatus of claim23 wherein said face has a slope angle that is a function of the anglebetween said grinding plane and said pivot axis.
 25. The apparatus ofclaim 19 wherein said mounting means and said tool holder form a slidingtongue-and-grove joint.
 26. A tool sharpener for sharpening at leastfirst and second complementary cutting surfaces of a cutting tool bygrinding a predetermined thickness of the complementary cuttingsurfaces, said tool sharpener comprising:a planar grinding surface; abody fixed with respect to said planar grinding surface; a mountingguide pivoted to said body for rotation about a pivot axis oriented at afirst angle with respect to said planar grinding surface; a tool holderhaving clamp means for adjustably clamping a cutting tool in apredetermined position within said tool holder; joint means having afirst joint fixed to said mounting guide and a second joint fixed tosaid tool holder, said joint means enabling said first joint to matewith said second joint such that said tool holder selectively mounts insaid mounting guide in first and second orientations, said joint meanshaving means for confining said tool holder to move with respect to saidmounting guide along a linear path directed parallel to said pivot axissuch that said first complementary cutting surface lies in said grindingplane when said tool holder is in said first orientation and saidcutting tool is being sharpened, and said second complementary cuttingsurface lies in said grinding plane when said tool holder is in saidsecond orientation and said cutting tool is being sharpened; and a limitmeans fixed on said mounting guide for limiting the extent of saidconfined path by an amount that is a function of said predeterminedthickness.
 27. The tool sharpener of claim 26 wherein said first jointmates with said second joint to form a sliding joint, and said toolholder is in an upright position when in said first orientation and isin an inverted position when in said second orientation.
 28. The toolsharpener of claim 27 wherein said tool holder comprises a V-blockcapable of receiving a cylindrical cutting tool, a clamping jaw, andmeans for engaging said clamping jaw with said V-block to selectivelyclamp a cylindrical cutting-tool in said V-block.
 29. The tool sharpenerof claim 28 wherein said body includes a planar platform sloped withrespect to said planar grinding surface, and said mounting guidepivotally slides on said planar platform with said pivot axisperpendicular to said planar surface and said planar platform forms anobtuse angle with said planar grinding surface.